How is Blockchain Revolutionizing Identity Management?

In recent years blockchain has reshaped how we think about digital identity. Previously, personal data were stored by big companies or governments, like keys in a single vault. Today, thanks to decentralized networks, each person can control their credentials, choosing who sees them and when.\n\nThis article summarizes a review of 47 studies published between 2019 and 2025, using the PRISMA method for scientific rigor. It starts with history: from centralized systems, through federated models (like "login with Google"), to decentralized blockchain architectures.\n\nNext, a taxonomy groups solutions into two main categories: generic ones designed for any sector, and domain‑specific ones, for health, education, travel, and more.\n\nFinally, it tackles security challenges across the whole identity lifecycle: interoperability between blockchains, revocation of rights (e.g., deleting an account), and resilience against future quantum computers.\n\nThe outcome is a map of still‑open gaps—technical, economic, and social—and a set of ideas for future research. For anyone aiming to build identity systems that are safer, more transparent, and sustainable, this work is an essential guide.

The review begins with the historical evolution of identity management systems (IDMS). Centralized models, typical of early computer systems, placed data control in a single entity, creating a critical single point of failure. Federated models introduced the concept of single sign‑on, yet retained dependence on third‑party providers.\n\nBlockchain‑based architectures introduce three key principles: decentralization, immutability, and transparency. Decentralization removes the single point of failure by distributing credential verification across independent nodes. Immutability ensures that identity transactions, once recorded, cannot be altered without network consensus. Transparency is balanced by privacy techniques such as zero‑knowledge proofs, which allow proving an attribute (e.g., age over 18) without revealing sensitive data.\n\nThe proposed taxonomy distinguishes between generic IDMS—often built on standards like Decentralized Identifiers (DIDs) and Verifiable Credentials (VCs)—and vertical solutions that embed sector‑specific business rules (e.g., GDPR compliance for healthcare).\n\nFrom a security perspective, the review highlights three critical vulnerabilities: interoperability (difficulty making heterogeneous blockchains communicate), revocation (how to invalidate compromised credentials), and quantum resilience (the threat that current signature algorithms could be broken by quantum computers). Proposed mitigations include revocation protocols based on Merkle trees, cross‑chain bridge solutions certified for interoperability, and adoption of post‑quantum signatures such as hash‑based schemes.\n\nFinally, the work stresses the need for sustainable economic models: transaction costs (gas) must remain low to keep IDMS accessible, and validator incentives must balance security and scalability. Future directions suggested include integration with edge‑computing networks, AI‑driven anomaly detection, and standardization of decentralized governance protocols.